If you take the birth control pill (oral contraceptive), you're probably happy with its convenience and reliability. Still, you may have questions about how birth control pills could affect your health, the benefits and risks of birth control pills, and newer options available.

Can I use birth control pills to delay or stop my period?

Yes, you can. Birth control pills were once only packaged as 21 days of active hormone pills and seven days of placebo pills. While taking placebo pills, menstrual period-like bleeding occurs.

Today women have many more options — from regimens with 24 days of active pills and four days of placebo pills to regimens that are all active pills.

Some extended-cycle pill regimens have active hormone pills every day for three months, followed by a week of placebo or low-dose estrogen pills. You experience menstrual bleeding during that week. Newer extended-cycle regimens involve taking active pills continuously for one year and can stop all menstrual bleeding.

Continuous or extended-cycle regimens have several potential benefits. They prevent hormone changes responsible for bleeding, cramping, headaches and other period-related discomforts. It can be convenient to skip a period during important events or trips. For women who experience iron deficiency due to heavy menstrual bleeding, using continuous regimens can reduce bleeding and there is less chance of developing iron deficiency.

Unscheduled bleeding and spotting often occur during the first few months on this type of regimen. It usually stops with time, but it continues in some women long after using the pills.

Do I need special pills or can I use ordinary birth control pills to prevent having a period?

There are birth control pill regimens designed to prevent bleeding for three months at a time or for as long as a year. But it's possible to prevent your period with continuous use of any birth control pill.

This means skipping the placebo pills and starting right away on a new pack. Continuous use of your birth control pills works best if you're taking a monophasic pill — with the same hormone dose in the three weeks of active pills.

If I plan to have a baby, how soon after stopping the birth control pill can I conceive?

Most women ovulate again about two weeks after stopping the pill. As soon as you ovulate again, you can get pregnant. If this happens during your first cycle off the pill, you may not have a period at all. Check a pregnancy test if you've had unprotected intercourse and your period hasn't returned.

Is there an advantage to waiting a few months after stopping the pill before trying to conceive?

Doctors were once concerned that if you conceived immediately after stopping the pill, you had a higher risk of miscarriage. However, these concerns have proved to be largely unfounded. The hormones in birth control pills don't remain in your system.

Most women start periods again a few weeks after they stop using the pill. However, if your periods were infrequent before you started taking the pill, they will likely be that way again after you stop the pill. Some women find that it takes a couple of months before they return to regular ovulation cycles. After stopping the pill, if you're not ready to conceive, then you may want to consider using a backup form of birth control.

What happens if I stop taking the birth control pill and my period doesn't come back?

If you don't have a period for several months, you may have what's known as post-pill amenorrhea. The pill prevents your body from making hormones involved in ovulation and menstruation. When you stop taking the pill, it can take some time for your body to return to normal production of these hormones.

Your period typically resumes within three months after you stop taking the pill. But some women, especially those who took the pill to regulate their menstrual cycles, may not have a period for several months.

If you don't have a period within three months, take a pregnancy test to make sure you're not pregnant and then see your doctor.

Will a pregnancy test be accurate if I'm taking the birth control pill?

You can get accurate results from a pregnancy test while you're on the pill. Pregnancy tests work by measuring a specific pregnancy-related hormone — human chorionic gonadotropin (HCG) — in your blood or urine. The active ingredients in birth control pills don't affect how a pregnancy test measures the level of HCG in your system.

What happens if I take birth control pills while pregnant?

Don't worry if you kept taking your birth control pill because you didn't know you were pregnant. Despite years of this accident happening, there's very little evidence that exposure to the hormones in birth control pills causes birth defects. Once you learn that you're pregnant, stop taking the birth control pill.

Can I use several birth control pills at once for emergency contraception?

It's possible to use standard estrogen-progestin birth control pills for emergency contraception, but check with your doctor for the proper dose and timing of the pills.

Certain types of pills are specifically designed to keep you from becoming pregnant if you've had unprotected vaginal intercourse. These medications are sometimes referred to as the "morning-after pill." Levonorgestrel pills (Take Action, Next Choice One Dose, and levonorgestrel .75) are available over-the-counter for women age 17 years and older. Younger women need a prescription for these medications.

Plan B One-Step — a single-dose regimen — is available over-the-counter for women of any age and should be used within 72 hours of unprotected intercourse. Plan B — a two-dose regimen — is available over-the-counter for women age 18 and older; those age 17 and younger need a prescription. These emergency contraceptives are available at drugstores, as well as health clinics and Planned Parenthood.

Ulipristal acetate (ella) is another type of pill approved for emergency contraception. It's a nonhormonal medication that prevents the effects of the body's natural hormone progesterone. It's available only by prescription. This medication is taken as a single dose for up to 5 days after unprotected intercourse.

Does how much I weigh reduce the effectiveness of emergency birth control pills?

If your body mass index (BMI) is more than 30 — especially if you use levonorgestrel — emergency contraception may not be as effective, and you could be at risk of still being pregnant after taking the pill or pills. BMI is not as much of a concern when using ulipristal or the copper intrauterine device.

I have taken birth control pills for years and want to stop. Can I stop at any time or should I finish my current pill packet?

In terms of your overall health, it makes little difference when you stop taking the pill. When you finally do stop the pill, you can expect some bleeding, which may change the rhythm of your menstrual cycle. But you can stop at any time.

Can I get pregnant during the week of nonactive (placebo) pills?

Taking the nonactive pills doesn't put you at higher risk of unintended pregnancy. If you're taking birth control pills exactly as directed, they're about 99 percent effective at preventing pregnancy.

But if you miss a pill — or several pills — during a cycle, you might be at higher risk of unintended pregnancy during that cycle. To be safe, use a backup form of contraception, such as a condom, especially if you miss several pills during a cycle.

Do birth control pills cause weight gain?

Many women think so. But studies have shown that the effect of the birth control pill on weight is small — if it exists at all.

Instead, you may be retaining more fluid, which can make you feel as if you've put on weight, particularly in your breasts, hips and thighs. The estrogen in birth control pills does affect fat (adipose) cells, making them larger but not more numerous.

How do birth control pills affect cancer risk?

Scientific evidence suggests using birth control pills for longer periods of time increases your risk of some cancers, such as cervical cancer and liver cancer, but the results aren't consistent. Most data shows that birth control pills don't increase your overall risk of cancer.

On the flip side, the birth control pill may decrease your risk of other types of cancer, including ovarian cancer and endometrial cancer.

Regarding breast cancer risk, some very early studies showed a link between pill use and breast cancer — likely due to the high estrogen dose found in contraceptive pills used in the 1970s. But, today's pills have a much lower estrogen dose, and more recent studies show no increase in breast cancer risk if you take birth control pills. Studies also have found no link between breast cancer risk and use of birth control pills in women who have a family history of breast cancer.

Do birth control pills affect cholesterol levels?

Birth control pills can affect your cholesterol levels. How much of an effect depends on the type of pill you're taking and what concentration of estrogen or progestin it contains. Birth control pills with more estrogen can have a slightly beneficial overall effect on your blood lipid levels. In general, though, the changes aren't significant and don't affect your overall health.

Do birth control pills affect blood pressure?

Birth control pills may slightly increase your blood pressure. If you take birth control pills, have your blood pressure checked regularly. If you already have high blood pressure, talk with your doctor about whether you should consider another form of birth control.

Can women older than age 35 continue taking birth control pills?

If you're healthy and you don't smoke, you can continue taking birth control pills after age 35. However, birth control pills aren't recommended if you're 35 or older and you smoke because of the risk of cardiovascular disease. In that case, you need to quit smoking before you can safely continue using birth control pills.

Can antibiotics decrease the effectiveness of birth control pills?

The effects of antibiotics on birth control pills may be overstated — except in the case of one antibiotic, rifampin (Rimactane). Rifampin does decrease the effectiveness of birth control pills in preventing ovulation, but this antibiotic isn't widely used today.